Wastewater treatment system

ABSTRACT

Disclosed is a system for treating wastewater. The system includes a microorganism clad structure positioned in a body of wastewater such that the microorganism clad structure is at least partially submerged in the body of wastewater. The apparatus also includes an aeration device, such as a propeller-type, surface mounted aeration device, supplying a horizontal flow of oxygenated water to the microorganisms attached to the microorganism clad structure such that the microorganisms may carry out a biological process.

RELATED APPLICATIONS

This application is a continuation of U.S. Application Ser. No.13/008,159 filed Jan. 18, 2011, now U.S. Pat. No. 8,110,108, which is acontinuation of U.S. application Ser. No. 12/724,293 filed Mar. 15,2010, now U.S. Pat. No. 7,892,433, which is a continuation of U.S.application Ser. No. 12/324,653 filed Nov. 26, 2008, now U.S. Pat. No.7,678,274, which is a continuation of U.S. application Ser. No.11/470,184 filed Sep. 5, 2006, now U.S. Pat. No. 7,465,394.

TECHNICAL FIELD

The disclosure generally relates to wastewater treatment systems. Moreparticularly, the disclosure pertains to apparatus, structures, systemsand methods for treating wastewater.

BACKGROUND

Wastewater treatment facilities, such as municipal, agricultural orindustrial wastewater treatment facilities, commonly utilize aerationtechniques in order to treat the wastewater. Aeration of the wastewaterhas been found to reduce or eliminate contaminants found in thewastewater by increasing the oxygen available to microorganisms whichbreak down contaminants during a biological process. Such techniqueshave been found to reduce the BOD (biochemical oxygen demand) and/orammonia levels found in wastewater. However, there is an ongoing need toprovide more efficient modes of treating wastewater.

SUMMARY

The disclosure is directed to apparatus, structures, systems and methodsfor treating wastewater.

Accordingly, one illustrative embodiment is an apparatus for treatingwastewater at a wastewater treatment facility. The apparatus includes amicroorganism clad structure positioned in a body of wastewater suchthat the microorganism clad structure is at least partially submerged inthe body of wastewater. The apparatus also includes an aeration device,such as a propeller-type, surface mounted aeration device, supplying ahorizontal flow of oxygenated water to the microorganisms attached tothe microorganism clad structure such that the microorganisms may carryout a biological process.

Another illustrative embodiment is a wastewater treatment systemincluding a wastewater containment reservoir containing a body ofwastewater. A baffled structure including a plurality of microorganismclad sheets of material are positioned in the wastewater containmentreservoir such that the plurality of microorganism clad sheets are atleast partially submerged in the body of wastewater. An aeration device,such as a propeller-type, surface mounted aeration device is positionedin the wastewater containment reservoir in proximity to the baffledstructure. The aeration device provides an oxygenated flow of wastewaterpast the microorganisms such that the microorganisms may carry out abiological process in the body of wastewater.

An illustrative method of treating wastewater includes the steps ofsubmerging a microorganism clad structure in a body of wastewater suchthat at least a portion of the microorganism clad structure is immersedin the body of wastewater. Oxygen may be injected into the body ofwastewater with an aeration device, creating a high velocity fluid jetin the body of wastewater, thereby providing a horizontal flow ofoxygenated water and/or nutrients past the microorganism clad structureto provide a favorable environment to carry out a biological process.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may be more completely understood in consideration of thefollowing detailed description of various embodiments in connection withthe accompanying drawings, in which:

FIG. 1 is a top view of an exemplary wastewater treatment system;

FIG. 2 is a side view of the exemplary wastewater treatment system ofFIG. 1;

FIG. 3 is a depiction of an exemplary horizontal flow which may beachieved within a wastewater treatment system;

FIG. 4A is a perspective view of an exemplary aeration device which maybe used in a wastewater treatment system;

FIG. 4B is a perspective view of another exemplary aeration device whichmay be used in a wastewater treatment system;

FIGS. 5A-5D illustrate an exemplary microorganism clad structure whichmay be used in association with an aeration device in a wastewatertreatment system;

FIG. 6 is another exemplary wastewater treatment system utilizing aplurality of aeration devices and a plurality of microorganism cladstructures; and

FIG. 7 is yet another exemplary wastewater treatment system utilizing aplurality of aeration devices and a plurality of microorganism cladstructures within a zone of the wastewater treatment system.

While the invention is amenable to various modifications and alternativeforms, specifics thereof have been shown by way of example in thedrawings and will be described in detail. It should be understood,however, that the intention is not to limit the invention to theparticular embodiments described. On the contrary, the intention is tocover all modifications, equivalents, and alternatives falling withinthe spirit and scope of the invention.

DETAILED DESCRIPTION

For the following defined terms, these definitions shall be applied,unless a different definition is given in the claims or elsewhere inthis specification.

All numeric values are herein assumed to be modified by the term“about”, whether or not explicitly indicated. The term “about” generallyrefers to a range of numbers that one of skill in the art would considerequivalent to the recited value (i.e., having the same function orresult). In many instances, the term “about” may be indicative asincluding numbers that are rounded to the nearest significant figure.

The recitation of numerical ranges by endpoints includes all numberswithin that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4,and 5).

As used in this specification and the appended claims, the singularforms “a”, “an”, and “the” include plural referents unless the contentclearly dictates otherwise. As used in this specification and theappended claims, the term “or” is generally employed in its senseincluding “and/or” unless the content clearly dictates otherwise.

The following detailed description should be read with reference to thedrawings in which similar elements in different drawings are numberedthe same. The detailed description and the drawings, which are notnecessarily to scale, depict illustrative embodiments and are notintended to limit the scope of the invention. The illustrativeembodiments depicted are intended only as exemplary. Selected featuresof any illustrative embodiment may be incorporated into an additionalembodiment unless clearly stated to the contrary.

Now referring to the drawings, an illustrative wastewater treatmentsystem 10 is illustrated in FIGS. 1 and 2. The wastewater treatmentsystem 10 includes a reservoir 12 containing a quantity of wastewater14. Although depicted as an oxidation oval, the reservoir 12 may be alagoon, such as an earthen or concrete lagoon, a basin, a pond, a tank,or the like. The wastewater 14, prior to being treated, includesundesired contaminants such as high levels of BOD and/or ammonia.

An aeration device 60 (or aeration device 160 as shown in FIG. 4B) ispositioned in the wastewater 14. As shown in FIG. 2, the aeration device60 may be positioned on the surface 15 of the wastewater 14, such that aportion of the aeration device 60 is submerged in the wastewater 14. Insome embodiments, the aeration device 60 may be a propeller-type,surface mounted aeration device. Some examples of suitable aerationdevices which may be utilized are disclosed in commonly owned U.S. Pat.Nos. 4,240,990; 4,280,911; 4,741,825; 4,774,031; 4,806,251; 4,882,099;4,954,295; 5,078,923 and 5,744,072, the disclosures of which are hereinincorporated by reference. In such embodiments, the propeller (shown inFIG. 4A) of the aeration device 60 is submerged below the surface 15 ofthe wastewater 14. The aeration device 60 may include one or morefloatation members 64 providing floatation of the aeration device 60 onthe surface 15 of the wastewater 14. However, in other embodiments theaeration device 60 may be positioned in the wastewater 14 by othermeans. For example, the aeration device 60 may be secured to a rigidmember and/or a wall of the reservoir 12, such that the aeration device60 may be supported in or over the wastewater 14.

The wastewater treatment system 10 also includes a microorganism cladstructure 20. The microorganism clad structure 20 may include a baffledstructure, such as a plurality of sheets 22 having a population ofmicroorganisms attached to the plurality of sheets 22. In someembodiments the sheets 22 may be spaced apart and generally parallel toone another. For example, in some embodiments the sheets 22 may bespaced apart at about 0.5 feet, about 1 foot, about 1.5 feet, about 2feet, about 2.5 feet, or about 3 feet intervals. Although some suitabledimensions are disclosed, one of skill in the art would understand thatdesired dimensions may deviate from those expressly disclosed. The spacebetween sheets 22 may be determined for a given application in order tooptimize wastewater flow therethrough.

The microorganism clad structure 20 may also include one or more, or aplurality of floatation devices 24 providing floatation of themicroorganism clad structure 20 on the surface 15 of the wastewater 14.However, in other embodiments, the microorganism clad structure 20 maybe positioned in the wastewater 14 by other means. For example, themicroorganism clad structure 20 may be secured to a rigid member and/ora wall of the reservoir 12 such that a portion of the microorganism cladstructure 20 may be supported in or over the wastewater 14.

The microorganism clad structure 20 may be positioned in the wastewater14 such that at least a portion of the plurality of sheets 22 aresubmerged in the wastewater 14. In some embodiments, the plurality ofsheets 22 may extend substantially to the bottom of the reservoir 12, orthe sheets 22 may extend downward any portion of the depth of thewastewater 14 in the reservoir 12. In some embodiments, the plurality ofsheets 22 may extend substantially the same distance. However, in otherembodiments, a portion of the sheets 22 may extend a different distancethan another portion of the sheets 22.

The aeration device 60 may be positioned in proximity to themicroorganism clad structure 20 such that the propeller of the aerationdevice 60 is directed toward an open end of the plurality of sheets 22.For example, in some embodiments, the aeration device 60 may bepositioned about 5 feet, about 10 feet, about 15 feet, or about 20 feetfrom the microorganism clad structure 20. The aeration device 60 mayintroduce oxygen (e.g., pure oxygen, ambient air, or other fluidcontaining an amount of oxygen) below the surface 15 of the wastewater14. For example, the aeration device 60 may inject oxygen into thewastewater 14, creating a fluid jet 35 directed toward the microorganismclad structure 20, dispersing oxygen and/or imparting velocity in thewastewater in a horizontal direction. Therefore, the aeration device 60may provide a horizontal flow (represented by arrows 30) of oxygenatedwater past the baffled structure (e.g., the plurality of sheets 22) ofthe microorganism clad structure 20 to provide a favorable environmentto carry out a biological process. The aeration device 60 may generate ahorizontal flow of oxygenated water through the plurality of sheets 22generating a positive velocity between the length of the channelscreated by the plurality of sheets 22.

An illustrative depiction of an exemplary horizontal flow which may beachieved with a propeller-type, surface mounted aeration device 60 isshown in FIG. 3. As shown in FIG. 3, a subsurface horizontal flow ofoxygenated water may be achieved through a substantial portion of thedepth of the body of wastewater 14.

In embodiments wherein the microorganism clad structure 20 and/or theaeration device 60 include floatation members, the microorganism cladstructure 20 and/or the aeration device 60 may be incorporated into anexisting reservoir, such as a lagoon, without extensive modifications ofthe existing structure and/or arrangement of the reservoir.

An exemplary aeration device 60, which may be used in the wastewatertreatment system 10, is further described in FIG. 4A. The aerationdevice 60 includes a frame 62 and one or more floatation members 64attached to the frame 62. The floatation members 64 allow the aerationdevice 60 to float on the surface of a body of wastewater. The aerationdevice 60 further includes a propeller 66 driven by a motor 68.Rotational motion generated by the motor 68 may be transferred to thepropeller 66 through the shaft 67. Oxygen may be directed through theshaft 67 to the diffuser 69, where the oxygen is introduced to the bodyof wastewater. Diffuser 69 can include a first disc 69A and a largersecond disc 69B. Oxygen introduced to the wastewater below the surfaceof the wastewater may exit the aeration device 60 in a high velocitystream of fine bubbles as it is diffused into the wastewater through thediffuser 69. In some embodiments, compressed oxygen may be pushedthrough the shaft 67, or in other embodiments, oxygen may be drawnthrough the shaft 67 by a vacuum created by rotation of the propeller66. In the embodiment illustrated in FIG. 4A, oxygen may be drawnthrough the shaft 67 by a vacuum created by rotation of the propeller66. The propeller 66, which provides mixing of the wastewater, and thediffuser 69, which diffuses oxygen into the wastewater, may bepositioned below the surface of the wastewater when the floatationmembers 64 are floating on the surface of the wastewater. For example,in some embodiments the propeller 66 and/or the diffuser 69 may bepositioned about 1 foot, about 2 feet, about 3 feet, or about 4 feetbelow the surface of the wastewater. Thus, oxygen, in the form of finebubbles, may be injected below the surface of the wastewater in a fluidjet.

Another exemplary aeration device 160, which may be used in thewastewater treatment system 10, is described in FIG. 4B. The aerationdevice 160 includes a frame 162 and one or more floatation members 164attached to the frame 162. The floatation members 164 allow the aerationdevice 160 to float on the surface of a body of wastewater. The aerationdevice 160 further includes a propeller 166 driven by a motor 168.Rotational motion generated by the motor 168 may be transferred to thepropeller 166 through the shaft 167. Oxygen may be directed through theshaft 167 to the diffuser 169, where the oxygen is introduced to thebody of wastewater. Diffuser 169 can include a first disc 169A and alarger second disc 169B. Oxygen introduced to the wastewater below thesurface of the wastewater may exit the aeration device 160 in a highvelocity stream of fine bubbles as it is diffused into the wastewaterthrough the diffuser 169. In some embodiments, compressed oxygen may bepushed through the shaft 167, or in other embodiments, oxygen may bedrawn through the shaft 167 by a vacuum created by rotation of thepropeller 166. In the embodiment illustrated in FIG. 4B, which may beconsidered a forced air aeration device, oxygen may be pulled through anintake 165 by a motor 161 and pushed through a tube 163 to the shaft167. Thus, the aeration device 160 may supply compressed air below thesurface of the wastewater in a high velocity stream of bubbles. Thepropeller 166, which provides mixing of the wastewater, and the diffuser169, which diffuses oxygen into the wastewater, may be positioned belowthe surface of the wastewater when the floatation members 164 arefloating on the surface of the wastewater. For example, in someembodiments the propeller 166 and/or the diffuser 169 may be positionedabout 1 foot, about 2 feet, about 3 feet, or about 4 feet below thesurface of the wastewater. Thus, oxygen, in the form of fine bubbles,may be injected below the surface of the wastewater in a fluid jet.

An exemplary microorganism clad structure 20, which may be a baffledstructure in some embodiments, that may be used in the wastewatertreatment system 10, is further described in FIGS. 5A-5D. Themicroorganism clad structure 20 may include a plurality of sheets 22.The plurality of sheets 22 may be spaced apart and generally parallel toone another. As shown in the Figures, the sheets 22 may be oriented in agenerally vertical orientation. However, in other embodiments, thesheets 22 may be oriented at an angle, such as an oblique or aperpendicular angle to the vertical. In some embodiments, the sheets 22may have a length of about 10 feet to about 40 feet, about 10 feet toabout 25 feet, or about 15 feet to about 20 feet. In some embodiments,the sheets may have a height of about 5 feet to about 20 feet, about 10feet to about 20 feet, or about 10 feet to about 15 feet. Although somesuitable dimensions are disclosed, one of skill in the art wouldunderstand that desired dimensions may deviate from those expresslydisclosed. The dimensions of the sheets 22 may be determined based onparameters of a specific application.

The plurality of sheets 22 may be secured to one or more, or a pluralityof support members. As shown in the Figures, the support member may be afloatation member 24, wherein an edge, such as the upper edge of thesheets 22 may be secured to the floatation member 24. The floatationmember 24 may take on any form which provides buoyancy to themicroorganism clad structure 20. For example, in some embodiments, thefloatation member 24 may be one or more air filled chambers, one or morefoam members, or other members exhibiting buoyancy in water. In theembodiment illustrated in FIGS. 5A-5D, each of the plurality of sheets22 is attached to a floatation member 24. However, in other embodiments,one or more sheets 22 may be attached to a single floatation member 24,as desired.

In some embodiments, the lower edge of the sheets 22 may include asupport member or ballast 21 or other means of maintaining the pluralityof sheets 22 submerged in the wastewater. For example, in someembodiments, each of the sheets 22 may be secured in a frame. In otherembodiments, the lower edge of the sheets 22 may be secured to oneanother, such that the plurality of sheets 22 maintain a desiredplacement within the wastewater. In yet other embodiments, the pluralityof sheets 22 may have a density greater than the density of thewastewater.

In some embodiments, the plurality of sheets 22 may be secured togetherwith one or more spacers 23 extending between adjacent sheets 22. Thespacers 23 may maintain the plurality of sheets 22 an equal, orotherwise consistent distance apart during operation. For example, inthe illustrated embodiment, spacers 23 may be located between adjacentsheets 22 at locations proximate the floatation members 24, the supportmembers or ballast 21, and/or one or more intermediate locations alongthe plurality of sheets 22.

Each of the plurality of sheets 22 may include one or more panels. Forexample, each sheet 22 may include three panels as shown in theillustrative embodiment. However, in other embodiments, the sheets 22may include 1, 2, 4, 5 or more panels. As shown in the Figures, each ofthe sheets 22 may include a first panel 27, a second panel 28, and athird panel 29. During operation, the microorganism clad structure 20may be positioned in the wastewater in proximity to the aeration device60 such that the first panel 27 is positioned closest to the aerationdevice 60. Due to the forces generated by the aeration device 60 increating a fluid jet 35 of fine bubbles, thereby instilling a horizontalflow in the wastewater, the first panel 27 may be stronger than thesecond panel 28 and the third panel 29 in order to endure hydrodynamicsof the wastewater. In some embodiments, the second panel 28, likewise,may be stronger than the third panel 29. Thus, the panels 27, 28 may beincrementally stronger than the adjacent panel 28, 29, respectively, inthe direction of the aeration device 60.

The plurality of sheets 22 may be formed of a material conducive tomicroorganism growth and attachment thereon. In some embodiments, theplurality of sheets 22 may be formed of a textile material. For example,the plurality of sheets 22 may be formed of a textile material, such asa non-biodegradable geo-textile, having a high effective surface area.In describing the textile material as having a high effective surfacearea, it is intended to mean the textile material has a surface areagreater than that computed by taking into account the outer periphery ofthe textile material alone. For example, the textile material may beporous, convoluted, woven, honeycombed, or may have other structureproviding a high effective surface area.

A population of microorganisms 40, or bio-film, is attached to theplurality of sheets 22. The population of microorganisms 40 may beattached to both sides of the sheets 22, or the population ofmicroorganisms 40 may be attached to only one side of the sheets 22 ifdesired. The population of microorganisms 40 may include bacteria, suchas BOD reducing bacteria, nitrifying bacteria and/or denitrifyingbacteria which may carry out a biological process, such as BODreduction, nitrification and/or denitrification in the wastewater.

BOD (biochemical oxygen demand) is an indicator commonly used to measurethe quality of a body of wastewater. BOD is a measurement of the amountof oxygen required to decompose the quantity of organic particles in thebody of wastewater. Thus, BOD reduction is a process in which the levelof BOD in a body of wastewater is reduced to improve the quality of thebody of wastewater. Heterotrophic bacteria are one type of bacteriawhich may be used to perform reduction of BOD levels in the wastewater.

Nitrification is the biological oxidation of ammonia (NH₃) with oxygen(O₂) which forms nitrite (NO₂ ⁻), followed by the oxidation of nitritesinto nitrates (NO₃ ⁻). Nitrification is an aerobic process utilizingoxygen to carry out the process. Nitrosomonas and nitrobacter are twotypes of nitrifying bacteria, which may be used to perform the oxidationof ammonia to nitrate in the wastewater. It has been found nitrificationmay be enhanced through the inclusion of a bio-film of microorganisms ona substrate, as opposed to free-floating bacterial colonies within thewastewater.

Denitrification is the biological process of reducing nitrates (NO₃ ⁻)into gaseous nitrogen (N₂). Denitrification is an anaerobic process,which takes place in the absence of oxygen. Pseudomonas are one type ofdenitrifying bacteria which may be used to perform reduction of nitratesin the wastewater.

The sheets 22 may be inoculated with a desired quantity of BOD reducingbacteria, nitrifying bacteria and/or denitrifying bacteria. The quantityof bacteria may be determined, among other factors, by the quantity ofwastewater to be treated, the duration of treatment, and/or the levelsof contaminants found in the wastewater.

As shown in FIG. 5C, the sheets 22 may include an aerobic zone 42, whichis an oxygen enriched zone, located at the surface of the sheet 22.Nitrifying bacteria may be located in the nitrification zone 42 in orderto carry out a nitrification process in the wastewater. Oxygenated watergenerated by the aeration device 60 may be readily available tonitrifying bacteria located in the nitrification zone 42. The sheets 22may also include a denitrification zone 44, which is an oxygen depletedzone, located within an internal portion of the sheet 22. As theinternal portion of the sheet 22 may be isolated from oxygen,denitrifying bacteria may be located in the denitrification zone 44 inorder to carry out a denitrification process in the wastewater. Thus, insome embodiments, nitrifying bacteria may be located in boundary layersbounding an internally located colonization of denitrifying bacteria. Inembodiments in which the sheets 22 include both nitrifying bacteria anddenitrifying bacteria, the wastewater may undergo nitrification and atleast partial denitrification, simultaneously.

Another illustrative wastewater treatment system 200 is illustrated inFIG. 6. The wastewater treatment system 200 includes a reservoir 210containing a body of wastewater 212. Contaminant enriched wastewater mayenter the reservoir 210 through influent pathway 214 and upon sufficienttreatment, contaminant depleted wastewater may exit the reservoir 210through effluent pathway 216.

A plurality of aeration devices 60 and microorganism clad structures 20may be positioned in the reservoir 210. As shown in FIG. 6, eachaeration device 60 may be paired with one microorganism clad structure20. Therefore, the combination of an aeration device 60 paired with amicroorganism clad structure 20 may be considered a wastewater treatmentunit 50. An aeration device 60, positioned in proximity to amicroorganism clad structure 20, may distribute nutrients and/or oxygenthrough mixing and aeration to the bio-film (i.e., the population ofmicroorganisms) in order to keep the bio-film healthy and tocontinuously renew the bio-film through facilitation of the sloughingprocess.

The wastewater treatment units 50, each including an aeration device 60and a microorganism clad structure 20, may be positioned in an array, orother desired orientation, within the reservoir 210. The arrangement ofthe wastewater treatment units 50 may be chosen to establish a desiredflow pathway of wastewater throughout the reservoir 210 as indicated bythe arrows in FIG. 6. For example, the wastewater treatment units 50 maybe arranged such that the aeration devices 60 provide a continuouscirculation of flow of oxygenated water through the microorganism cladstructures 20. Such an arrangement allows for multiple passes ofwastewater past the microorganism clad structures 20 to enhance thetreatment efficiency of the wastewater treatment system 200, byincreasing the contact time between the wastewater 212 and the bio-filmattached to the microorganism clad structure 20. Additionally, bymaintaining the wastewater 212 in a continuous circulation pathway,solids found in the wastewater 212 may remain in suspension and notsettle to the bottom of the reservoir 210.

It has been found that water temperature has a signification impact onnitrification by nitrifying bacteria in wastewater. Thus, nitrificationrates are directly related to seasonal temperature changes. It has beenfound that nitrification is maximized when water temperatures aregreater than 20° C. The rate of nitrification decreases as watertemperature drops. As water temperatures approach 0° C., nitrificationis inhibited and the rate of nitrification approaches zero. Therefore,in geographic regions which experience nitrification inhibitingtemperatures, sufficient nitrification occurs at only certain times ofthe year. The use of the aeration devices 60 in conjunction withmicroorganism clad structures 20 within a wastewater reservoir asdisclosed herein, may increase the water temperature of the wastewaterdue to the continuous circulation of the wastewater through thereservoir. In addition, the concentrated biological communities found onthe microorganism clad structures 20 may significantly increase thebiological population density in the system, leading to an increase inthe sludge age and hence the residence time of the microorganisms.Therefore, sufficient nitrification within the reservoir may be achievedfor a greater portion of the year, or in many cases year-round. Thehigher rates of nitrification during cold weather may be attributed tothe energy added to the wastewater by the mixing and/or high fluid flowvelocities generated by the aeration device 60 combined with theincrease in biological population density and residence time.

Another illustrative wastewater treatment system 300 is illustrated inFIG. 7. The wastewater treatment system 300 is illustrated as includingmultiple stages. A first stage may be a BOD (biological oxygendemand)/TSS (total suspended solids) reduction zone 315 in whichaeration may be utilized to reduce the BOD/TSS levels of the wastewater.Aeration may be performed with an aerator or multiple aerators, such asthe aeration device 60 illustrated in FIG. 4A or the aeration device 160illustrated in FIG. 4B, or aeration may be performed by another aerationdevice known in the art. In some embodiments, such as illustrated inFIG. 7, one or more, or a plurality of microorganism clad structures 20may also be located in the BOD/TSS reduction zone 315. However, in otherembodiments, the BOD/TSS reduction zone 315 may be devoid ofmicroorganism clad structures 20.

A second stage may be a nitrification/denitrification zone 325 in whichnitrification and/or denitrification occurs. In some embodiments, thewastewater treatment system 300 may be configured such thatnitrification and/or denitrification occurs almost exclusively in thenitrification/denitrification zone 325. Furthermore, a discharge zone335, which in some embodiments may be considered a quiescent zone, maycontain treated wastewater discharged from thenitrification/denitrification zone 325.

A baffle 310 may separate the BOD/TSS reduction zone 315 from thenitrification/denitrification zone 325. The baffle 310 may include anopening 318 allowing passage of wastewater from the BOD/TSS reductionzone 315 to the nitrification/denitrification zone 325. Likewise, abaffle 320 may separate the nitrification/denitrification zone 325 fromthe discharge zone 335. The baffle 320 may include an opening 328allowing passage of wastewater from the nitrification/denitrificationzone 325 to the discharge zone 335.

The BOD/TSS reduction zone 315 may include one or a plurality ofaerators 360, which in some instances may be the aeration device 60illustrated in FIG. 4A or the aeration device 160 illustrated in FIG.4B, to perform aeration in the BOD/TSS reduction zone 315, or aerationmay be performed by another aeration device known in the art. In someembodiments, one or more microorganism clad structures 20 may beincluded in the BOD/TSS reduction zone 315 to improve BOD removal incertain applications, such as in instances where the hydraulic retentiontime of the wastewater is determined to be too short and/or whereinfluent BOD loading is determined to be too high. However, in otherembodiments BOD/TSS reduction zone 315 may be devoid of microorganismclad structures 20. In the illustrative embodiment, influent wastewaterenters the BOD/TSS reduction zone 315 by the influent pathwayschematically depicted as element 305. The aerators 360 create acontinuous flow of wastewater in the BOD/TSS reduction zone 315, inwhich a quantity of wastewater may steadily migrate into thenitrification/denitrification zone 325 through the opening 318.

The nitrification/denitrification zone 325 may include a plurality ofaeration devices 60 and microorganism clad structures 20. As shown inFIG. 7, each aeration device 60 in the nitrification/denitrificationzone 325 may be paired with one microorganism clad structure 20.Therefore, the combination of an aeration device 60 paired with amicroorganism clad structure 20 may be considered a wastewater treatmentunit 50. The aeration devices 60 located in thenitrification/denitrification zone 325 create a continuous flow ofwastewater through and past the microorganism clad structures 320, thusproviding a flow of oxygenated water through the microorganism cladstructures 20. As shown in FIG. 7, the wastewater treatment units 50 arearranged in a circular pattern such that a circular flow pathway isestablished in the nitrification/denitrification zone 325. Therefore,the continuous cyclic flow of the wastewater provides recirculation ofthe wastewater past the bio-film (i.e., the population ofmicroorganisms) attached to the microorganism clad structures 20multiple times in order to increase treatment efficiency of thewastewater. The aeration devices 60 may distribute nutrients throughmixing and aeration to the bio-film in order to keep the bio-filmhealthy and to continuously renew the bio-film through facilitation ofthe sloughing process. Thus, the bio-film may carry out a biologicalprocess, such as nitrification and/or denitrification of the wastewaterin the nitrification/denitrification zone 325.

The opening 328 between the nitrification/denitrification zone 325allows a steady flow of wastewater to migrate into the discharge zone335. Zone 335 may typically be a settling zone where suspended solidsare settled prior to effluent discharge. From the discharge zone 335,the treated wastewater may exit the wastewater treatment system 300 byway of the effluent pathway schematically depicted as element 345.

The disclosed wastewater treatment systems may be incorporated intoexisting wastewater treatment reservoirs, such as lagoons, with minimalmodifications to the reservoir. Thus, installation of the disclosedwastewater treatment systems in an existing reservoir may be founduncomplicated, without extensive modifications of the existingreservoir. The quantity and position of the components may be determinedby the size of the body of wastewater, desired contaminant reduction ofthe wastewater, and/or the time allocated to treatment of a specifiedquantity of wastewater. Thus, the layout of the components may becustomized based on the specific parameters of the reservoir in order tomaximize efficiency of the system. Furthermore, the disclosed wastewatertreatment systems may be installed in static bodies of wastewater or incontinuous flow bodies of wastewater.

Those skilled in the art will recognize that the present invention maybe manifested in a variety of forms other than the specific embodimentsdescribed and contemplated herein. Accordingly, departure in form anddetail may be made without departing from the scope and spirit of thepresent invention as described in the appended claims.

1. (canceled)
 2. A wastewater treatment system comprising: a reduction zone at least partially defined by a first baffle, said reduction zone comprising: an influent pathway; plurality of floating microorganism clad structures at least one reduction zone aeration device adapted to create a continuous flow of wastewater within the first reduction zone; and a first exit opening; a nitrification/denitrification zone at least partially defined by a second baffle, said nitrification/denitrification zone being adapted to receive wastewater from the reduction zone through the first exit opening and comprising: a plurality of nitrification/denitrification zone aeration devices a plurality of nitrification/denitrification zone microorganism clad structures; and a second exit opening; and a discharge zone adapted to receive wastewater from the nitrification/denitrification zone through the second exit opening, said discharge zone including an effluent exit pathway, wherein the reduction zone is adapted to reduce biological oxygen demand and total suspended solids associated with the wastewater, further wherein the nitrification/denitrification zone is adapted to carry out at least one of biological oxidation of ammonia and biological reduction of nitrates.
 3. The wastewater treatment system of claim 2, wherein the at least one reduction zone aeration device is a floating aeration device.
 4. The wastewater treatment system of claim 2, wherein the plurality of nitrification/denitrification zone aeration devices is a plurality of floating aeration devices.
 5. The wastewater treatment system of claim 2, wherein the plurality of nitrification/denitrification zone microorganism clad structures is a plurality of floating microorganism clad structures comprising a plurality of partially submerged sheets arranged in parallel, said plurality of partially submerged sheets providing a media for microorganism attachment thereto.
 6. The wastewater treatment system of claim 5, wherein the plurality of partially submerged sheets include nitrifying microorganisms which perform a nitrification process.
 7. The wastewater treatment system of claim 5, wherein the plurality of partially submerged sheets include denitrifying microorganisms which perform a denitrification process.
 8. The wastewater treatment system of claim 5, wherein the plurality of partially submerged sheets include nitrifying microorganisms which perform a nitrification process and denitrifying microorganisms which perform a denitrification process.
 9. The wastewater treatment system of claim 2, wherein each nitrification/denitrification zone aeration device is associated with one nitrification/denitrification zone microorganism clad structure.
 10. The wastewater treatment system of claim 9, wherein each nitrification/denitrification zone aeration device and associated nitrification/denitrification zone microorganism clad structure is arranged as a unit within a generally circular array of units adapted to provide continuous recirculation of wastewater within the nitrification/denitrification zone.
 11. The wastewater treatment system of claim 2, further comprising a supply of nutrients adapted to distribute nutrients within the nitrification/denitrification zone.
 12. The wastewater treatment system of claim 2, wherein the reduction zone further comprises at least one reduction zone floating microorganism clad structure comprising a plurality of partially submerged sheets arranged in parallel, said plurality of partially submerged sheets providing a media for microorganism attachment thereto.
 13. The wastewater treatment system of claim 12, wherein the at least one reduction zone floating microorganism clad structure includes microorganisms adapted to reduce biological oxygen demand.
 14. The wastewater treatment system of claim 2, wherein the discharge zone is adapted to allow suspended solids to settle thereby reducing the quantity of suspended solids present in the wastewater received from the nitrification/denitrification zone before the wastewater leaves the discharge zone via the effluent exit pathway.
 15. The wastewater treatment system of claim 2, wherein at least one reduction zone aeration device is adapted to increase a concentration of at least one atmospheric gas within the wastewater relative to a concentration of that atmospheric gas in the wastewater entering the reduction zone aeration device.
 16. The wastewater treatment system of claim 2, wherein at least some of the plurality of nitrification/denitrification aeration devices are adapted to increase a concentration within the wastewater of at least one atmospheric gas relative to a concentration of that atmospheric gas in the wastewater entering that nitrification/denitrification zone aeration device. 